1. Corrosion is the process of:
A) Melting of metals
B) Chemical deterioration of metals
C) Freezing of metals
D) Shaping of metals
Answer: B) Chemical deterioration of metals
2. Rust is chemically known as:
A) Iron oxide
B) Hydrated iron(III) oxide
C) Iron carbonate
D) Iron sulfate
Answer: B) Hydrated iron(III) oxide
3. The chemical formula of rust is:
A) FeO
B) Fe₂O₃
C) Fe₂O₃·xH₂O
D) Fe₃O₄
Answer: C) Fe₂O₃·xH₂O
4. Rusting of iron requires:
A) Oxygen only
B) Water only
C) Oxygen and water
D) Carbon dioxide only
Answer: C) Oxygen and water
5. Which metal does not rust?
A) Iron
B) Copper
C) Aluminum
D) Gold
Answer: D) Gold
6. The green coating on copper is called:
A) Rust
B) Patina
C) Tarnish
D) Scale
Answer: B) Patina
7. Galvanization involves coating iron with:
A) Copper
B) Silver
C) Zinc
D) Tin
Answer: C) Zinc
8. Which of the following prevents rusting?
A) Painting
B) Oiling
C) Greasing
D) All of these
Answer: D) All of these
9. Stainless steel resists corrosion due to presence of:
A) Copper
B) Chromium
C) Zinc
D) Tin
Answer: B) Chromium
10. Rusting is an example of:
A) Physical change
B) Chemical change
C) Nuclear change
D) Mechanical change
Answer: B) Chemical change
11. Which environment accelerates rusting?
A) Dry air
B) Moist air
C) Vacuum
D) Inert gas
Answer: B) Moist air
12. The reddish-brown layer formed on iron is:
A) Metal
B) Alloy
C) Rust
D) Salt
Answer: C) Rust
13. Corrosion of silver leads to formation of:
A) Silver oxide
B) Silver nitrate
C) Silver sulfide
D) Silver chloride
Answer: C) Silver sulfide
14. Electrochemical corrosion involves:
A) No chemical reaction
B) Only heat
C) Redox reactions
D) Physical forces
Answer: C) Redox reactions
15. Which factor does NOT affect corrosion?
A) Temperature
B) Humidity
C) Nature of metal
D) Color of metal
Answer: D) Color of metal
16. Anodizing is commonly used to protect:
A) Iron
B) Copper
C) Aluminum
D) Gold
Answer: C) Aluminum
17. Rusting is faster in:
A) Pure water
B) Salt water
C) Distilled water
D) Dry air
Answer: B) Salt water
18. The substance that gets oxidized during rusting is:
A) Oxygen
B) Iron
C) Water
D) Carbon dioxide
Answer: B) Iron
19. Corrosion causes metal to become:
A) Stronger
B) Shiny
C) Weaker
D) Magnetic
Answer: C) Weaker
20. Which gas helps in rust formation?
A) Nitrogen
B) Hydrogen
C) Oxygen
D) Helium
Answer: C) Oxygen
21. Sacrificial protection uses a more:
A) Noble metal
B) Reactive metal
C) Expensive metal
D) Heavy metal
Answer: B) Reactive metal
22. In galvanization, zinc acts as:
A) Cathode
B) Anode
C) Neutral metal
D) Insulator
Answer: B) Anode
23. Corrosion is generally a:
A) Reduction process
B) Oxidation process
C) Neutralization
D) Polymerization
Answer: B) Oxidation process
24. Which metal forms a protective oxide layer naturally?
A) Iron
B) Aluminum
C) Silver
D) Lead
Answer: B) Aluminum
25. Rusting of iron increases in presence of:
A) Acid
B) Base
C) Sugar
D) Oil
Answer: A) Acid
26. The process of coating iron with tin is called:
A) Galvanizing
B) Tinning
C) Alloying
D) Smelting
Answer: B) Tinning
27. Which of the following is NOT a method of corrosion prevention?
A) Painting
B) Electroplating
C) Increasing moisture
D) Alloy formation
Answer: C) Increasing moisture
28. Rusting is an example of:
A) Slow reaction
B) Fast reaction
C) Instant reaction
D) Explosion
Answer: A) Slow reaction
29. The presence of electrolytes increases corrosion due to:
A) Reduced conductivity
B) Increased conductivity
C) Reduced oxidation
D) Cooling effect
Answer: B) Increased conductivity
30. Cathodic protection works by making the metal:
A) Anode
B) Cathode
C) Neutral
D) Oxide
Answer: B) Cathode